Americans are increasingly seeking care from massage therapists for relief of back pain. Unfortunately, little is known about the effectiveness of the most readily available form of massage, Swedish massage for relaxation. Relaxation massage is intended to relax the whole body, in contrast to more therapeutically-oriented forms of massage that involve manipulation of the muscles, fascia or ligaments believed responsible for the pain. Although relaxation massage is taught in almost all massage schools and used by most US massage therapists, its effectiveness for back pain has never been evaluated. The primary aim of this study is to determine if relaxation massage is an effective treatment for chronic low back pain. If found effective, relaxation massage would represent a widely available and safe alternative to commonly prescribed muscle relaxant medications that can have side effects and a risk of habituation. The study will also allow us to determine if relaxation massage is more or less effective than therapeutic massage in reducing short-term and long-term pain and dysfunction due to back pain. 399 health plan members (133 per group) with non-specific low back pain lasting at least 3 months will be randomized to relaxation massage, therapeutic massage, or a control group that receives no treatment beyond their usual care. Massage therapists will provide 10 treatments over 10-weeks. The primary outcomes, function and bothersomeness of low back pain, will be assessed at baseline and 4, 10, 26, and 52 weeks after randomization by interviewers masked to treatment. This study will also explore the ability of physical, psychosocial, and clinical baseline characteristics of patients with chronic low back to predict which patients will benefit most from each type of massage. The results of this study will clarify the value of the most common form of massage for treating one of the most common, challenging, and expensive health problems plaguing developed countries. The findings will help physicians make informed and confident referrals, consumers and insurers make safe and cost-effective choices, and massage schools make responsible curriculum decisions.